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https://github.com/sap-samples/cf-autoscaler-custom-metrics-mtls

Sample Golang app that demonstrates the use of the custom metrics feature in Application Autoscaler using mTLS authentication.
https://github.com/sap-samples/cf-autoscaler-custom-metrics-mtls

application-autoscaler cloud-foundry custom-metrics golang mtls sample sample-code sap-btp

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Sample Golang app that demonstrates the use of the custom metrics feature in Application Autoscaler using mTLS authentication.

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# Demonstrate Custom Metrics Feature in Application Autoscaler



## Description



The SAP Business Technology Platform (BTP) provides a runtime environment for running your applications at scale.

This repository include a sample Golang application that use the Cloud Foundry runtime for SAP BTP.



Check out the step-by-step guide on [SAP Blogs](https://blogs.sap.com/?p=1613870&preview=true&preview_id=1613870)



Application Autoscaler, an autoscaling service in Cloud Foundry Runtime, automatically adds or removes application instances/nodes based on the workload. This can be done by defining an autoscaling policy, containing scaling rules.

This repository explains about how to send custom metrics to CF Autoscaler Service using mTLS authentication



### Application Autoscaler Use Cases

- Is your Cloud Foundry (CF) application unable to cope with large amounts of requests during peak hours?

- Have you seen a decrease in application performance in high-traffic conditions?

- Are you looking to reduce your runtime costs when there is less traffic?

- Do you want to scale your CF application based on your custom metrics (other than CPU, memory, throughput, reponsetime) ?



This tutorial includes the following steps

 - Build and Deploy sample Golang Application

 - Create Autoscaler Service Instance

 - Bind App with Autoscaler Service

 - Start Golang App

 - Send Custom Metrics to Autoscaler Service

 - Monitor Scale-Out and Scale-In 



## Requirements



- You should have access to Cloud Foundry Runtime



## Build and Deploy sample Golang Application



### Build App

#### Option 1 `env GOOS=linux GOARCH=amd64 go build -o build/golang-autoscaler-custom-metrics`

#### Option 2 `make build`



### Run Test



`make test`



### Deploy App



`cf push --no-start -f deploy/app-manifest.yml -p deploy/build`



sample-output

```shell

$ cf push --no-start -f deploy/app-manifest.yml -p deploy/build

Pushing app golang-autoscaler-custom-metrics to org ak_autoscalerxxx / space ak-test-space as [email protected]...

Applying manifest file deploy/app-manifest.yml...



Updating with these attributes...

  ---

  applications:

  - name: golang-autoscaler-custom-metrics

    disk-quota: 128M

    instances: 1

    path: /Users/development/golang-autoscaler-custom-metrics/deploy/build

    memory: 128M

+   default-route: true

    stack: cflinuxfs4

    buildpacks:

      binary_buildpack

    command: ./golang-autoscaler-custom-metrics

Manifest applied

All files found in remote cache; nothing to upload.

Waiting for API to complete processing files...



name:              golang-autoscaler-custom-metrics

requested state:   stopped

routes:            golang-autoscaler-custom-metrics.cfapps.sap.hana.ondemand.com

last uploaded:

stack:

buildpacks:



type:            web

sidecars:

instances:       0/1

memory usage:    128M

start command:   ./golang-autoscaler-custom-metrics

     state   since                  cpu    memory   disk     details

#0   down    2022-12-30T14:22:58Z   0.0%   0 of 0   0 of 0



```



## Create Autoscaler Service Instance



```shell

$ cf create-service autoscaler standard ak-test-autoscaler

Creating service instance ak-test-autoscaler in org ak_autoscalerxxx / space ak-test-space as as [email protected]...



Service instance ak-test-autoscaler created.

OK

```

## Bind App with Autoscaler Service

`$ cf bind-service golang-autoscaler-custom-metrics ak-test-autoscaler -c deploy/custom-metrics-policy.json`



```shell

$ cf bind-service golang-autoscaler-custom-metrics ak-test-autoscaler -c deploy/custom-metrics-policy.json

Binding service instance ak-test-autoscaler to app golang-autoscaler-custom-metrics in org ak_autoscalerxxx / space ak-test-space as [email protected]...

OK



TIP: Use 'cf restage golang-autoscaler-custom-metrics' to ensure your env variable changes take effect



```

### Check VCAP_SERVICE Environment Variable



```shell

$ cf env golang-autoscaler-custom-metrics

Getting env variables for app golang-autoscaler-custom-metrics in org ak_autoscalerxxx / space ak-test-space as [email protected]...

System-Provided:

VCAP_SERVICES: {

  "autoscaler": [

    {

      "binding_guid": "c02fba90-83b2-4753-a31f-1d0827978632",

      "binding_name": null,

      "credentials": {

        "custom_metrics": {

          "mtls_url": "https://autoscaler-metrics-mtls.cf.xxx.com",

          "password": "xxxxxxxxx",

          "url": "https://autoscaler-metrics.cf.xxx.com",

          "username": "xxxxxxxxx"

        }

      },

      "instance_guid": "3eeac1a2-ced1-4748-a3b4-a87188a7d3c6",

      "instance_name": "ak-test-autoscaler",

      "label": "autoscaler",

      "name": "ak-test-autoscaler",

      "plan": "standard",

      "provider": null,

      "syslog_drain_url": null,

      "tags": [

        "autoscaler",

        "app-autoscaler",

        "cf-autoscaler"

      ],

      "volume_mounts": []

    }

  ]

}



VCAP_APPLICATION: {

  ...

  ....

  ...



```

## Start Golang App

`cf start golang-autoscaler-custom-metrics`



```shell

cf start golang-autoscaler-custom-metrics

Starting app golang-autoscaler-custom-metrics in org ak_autoscalerxxx / space ak-test-space as [email protected]...



Staging app and tracing logs...

   Downloading binary_buildpack...

   Downloaded binary_buildpack

   Cell 038ca894-a748-49d5-85eb-be08569dfe48 creating container for instance 95b8140e-065c-4116-8c42-085f3f33db27

   Cell 038ca894-a748-49d5-85eb-be08569dfe48 successfully created container for instance 95b8140e-065c-4116-8c42-085f3f33db27

   Downloading app package...

   Downloading build artifacts cache...

   Downloaded build artifacts cache (215B)

   Downloaded app package (6M)

   -----> Binary Buildpack version 1.0.47

   Exit status 0

   Uploading droplet, build artifacts cache...

   Uploading droplet...

   Uploading build artifacts cache...

   Uploaded build artifacts cache (216B)



Starting app golang-autoscaler-custom-metrics in org ak_autoscalerxxx / space ak-test-space as [email protected]...



Waiting for app to start...



Instances starting...

Instances starting...

Instances starting...



name:              golang-autoscaler-custom-metrics

requested state:   started

routes:            golang-autoscaler-custom-metrics.cfapps.sap.hana.ondemand.com

last uploaded:     Fri 30 Dec 16:04:06 CET 2022

stack:             cflinuxfs4

buildpacks:

	name               version   detect output   buildpack name

	binary_buildpack   1.0.47    binary          binary



type:           web

sidecars:

instances:      1/1

memory usage:   128M

     state     since                  cpu    memory      disk        details

#0   running   2022-12-30T15:04:16Z   0.0%   0 of 128M   0 of 128M



```



## Send Custom Metrics to Autoscaler Service



Scale out > `$ curl https://golang-autoscaler-custom-metrics.cfapps.abc.com/busy/301`



```shell

Every 2.0s: cf app golang-autoscaler-custom-metrics                                                                                                                                          XNQNV6VGJC: Fri Dec 30 16:19:22 2022



Showing health and status for app golang-autoscaler-custom-metrics in org ak_autoscalerxxx / space ak-test-space as [email protected]...



name:              golang-autoscaler-custom-metrics

requested state:   started

routes:            golang-autoscaler-custom-metrics.cfapps.sap.hana.ondemand.com

last uploaded:     Fri 30 Dec 16:16:35 CET 2022

stack:             cflinuxfs4

buildpacks:

        name               version   detect output   buildpack name

        binary_buildpack   1.0.47    binary          binary



type:           web

sidecars:

instances:      2/2

memory usage:   128M

     state     since                  cpu    memory          disk            details

#0   running   2022-12-30T15:16:44Z   0.9%   23.6M of 128M   10.9M of 128M

#1   running   2022-12-30T15:18:13Z   0.9%   22.9M of 128M   10.9M of 128M



```



Scale In > `$ curl https://golang-autoscaler-custom-metrics.cfapps.abc.com/not-busy/190`



## License

Copyright (c) 2023 SAP SE or an SAP affiliate company. All rights reserved. This project is licensed under the Apache Software License, version 2.0 except as noted otherwise in the [LICENSE](LICENSE) file.